DE69103443T2 - Process for the production of delivery systems from polyvinyl acetate. - Google Patents

Description

This invention relates to an improved method for manufacturing a delivery system in which a core material, e.g. a sweetener, is protected by a matrix coating with the ability to control the release of the core material. The delivery system can be incorporated into chewing gum and confectionery compositions to provide a prolonged release of the core material. In particular, this invention relates to an improved method for the large-scale manufacture of such delivery systems.

Coatings for sweeteners to delay or prolong sweetness and to stabilize sensitive sweeteners are known. Nevertheless, certain sweeteners, such as aspartame, are particularly difficult to coat because aspartame crystals are rod-, needle-, or dendritic in shape and are particularly difficult to moisten. Consequently, it is very difficult to coat aspartame crystals using conventional mixing and spray coating techniques. To effectively protect aspartame, a coating must (a) be moist and adhere to the crystalline surface including the needle and rod ends and other deformations of the crystal, (b) form a film of a coating designed to provide a barrier to degradation factors, e.g. humidity, pH changes, temperature changes and reactive chemicals, and (c) be flexible enough to accommodate irregularities in the crystal surface without cracking as a result of the mechanical stresses that occur when the sweetener is incorporated into the final product. Attempts to coat aspartame Crystals using mixing and spraying techniques to apply simple mixtures of fat and lecithin resulted in poor wetting and patchy coating of the crystals and consequently unacceptable protection of the core material against moisture and other degradation factors. In addition, many of these coating materials require solvents and water for application. Such solvents and water impair the stability of hydrophilic unstable materials such as aspartame.

Known means of coating difficult-to-coat materials such as aspartame generally involve spray coating the core material in a fluidized bed or mixing the core material with molten coating material and pulverizing the cooled mixture. In fluidized bed spray coating, a mass of the core material is suspended in an air stream passing through a zone of atomized droplets of the coating material. Spray coating of aspartame in a fluidized bed system is difficult because aspartame is a low density material and has a high surface area to weight ratio and poor wetting properties. When a molten mixture of coating material and sweetener is formed, pulverization of the solidified mixture results in particles that are incompletely coated and not adequately protected. Coating these difficult-to-coat materials on a large scale is even more difficult.

US Patent No. 4,384,004 to Cea et al. discloses solid aspartame particles encapsulated with a coating material selected from the group consisting of cellulose, cellulose derivatives, arabinogalactin, gum arabic, polyolefins, waxes, vinyl polymers, gelatin, zein and mixtures thereof. The aspartame particles are atomized in a zone of liquid droplets of the coating material are suspended in a stream of air flowing through it. More than one coating can be applied, with the inner coating being water-soluble and the outer coating being water-soluble.

It is known from US Pat. Nos. 4,122,195 and 4,139,939 to Bahoshy et al. to coat aspartame with a non-gelatinized acid ester of a substituted dicarboxylic acid by spray drying a mixture of aspartame and a film-forming agent with a material such as gum arabic or the reaction product of a compound with a polyvalent metal ion.

US Patent 4,374,858 by Glass et al. describes a sweetened chewing gum with aspartame, which is characterized by improved sweetness stability. In contrast to incorporating aspartame into the chewing gum mixture, the chewing gum piece has aspartame applied to the gum surface

From US-PS 4 105 801 by Degliotti, a candy mass with a core part and an outer skin covering the core part is known. The outer skin consists of an intimate mixture of xylitol microcrystals with a solid fatty substance in a ratio of 0.5 to 15 parts by weight of fatty substance to 100 parts by weight of xylitol. The fatty substance is preferably mono-, di- or triglycerides with a melting range between 20ºC and 60ºC.

US-PS 3 389 000 to Toyonaka et al. discloses a spray drying process for producing granular coated nucleoside-5-phosphates. The coatings can be edible animal and vegetable fats with a melting point between 40ºC and 100ºC, eg hydrogenated oils including soybean oil, cottonseed oil, almond oil, castor oil, linseed oil, mustard oil, olive oil, grapefruit seed oil, palm oil, palm kernel oil, Rapeseed oil, rice bran oil and the like, and mixtures of these oils.

Berling U.S. Patent No. 4,382,924 discloses liquid oral dosage forms for vitamins or drugs comprising an edible oil, a high-sweetening, lipid-soluble sweetener such as saccharin, and a lipid-soluble flavoring agent. The edible oil may consist of a polyol fatty acid ester having at least four fatty acid ester groups, each fatty acid having about 8 to 22 carbon atoms. The oil, sweetener and flavoring oil are heated and mixed and then cooled to provide a palatable liquid dosage form.

For a general discussion of spray application of fatty materials to sweeteners and the like, see U.S. Patent Nos. 3,949,094 and 3,976,794 to Johnson and 3,867,556 to Darragh. U.S. Patent No. 4,293,572 to Silva et al. discloses the application of a dispersion of an emulsified fat with a solution of dextrin, saccharin or a polysaccharide to a food product as a moisture barrier.

European Patent Application 81 110 320.0, published June 16, 1982, by Ajinomoto-Co., Inc. describes a stabilized dipeptide-based sweetener composition containing, by weight, (a) 20 to 60% solid fat, (b) 10 to 30% emulsifier, (c) 10 to 30% polysaccharide, and (d) not more than 30% of a dipeptide sweetener. The compositions are prepared by spray coating the sweetener or heating and mixing a mixture of sweetener and coating material, cooling the mixture, and then pulverizing the mixture to form a powder or granules.

US Patent No. 4,597,970 to Sharma et al. discloses a delivery system in which a sweetener is coated with a mixture of a fatty acid or wax, lecithin and a monoglyceride. The delivery system supports and controls the release of the sweetener.

U.S. Patent No. 4,816,265 to Cherukuri et al. discloses a chewing gum composition with a sweetener delivery system. The latter consists essentially of (a) at least one solid natural or artificial high intensity sweetener in an amount of about 0.01% to about 50%, (b) an emulsifier in an amount of about 0.5% to about 20%, and (c) polyvinyl acetate with a molecular weight of about 2,000 to about 14,000 in an amount of about 40% to about 93%. The process described for producing the sweetener delivery system is intended for small-scale production of coated material and is not suitable for implementation on a large-scale.

Thus, numerous processes are known for producing coated sweeteners with varying degrees of protection and the ability to control the release of the core material. However, none of these processes can be effectively carried out on a large scale for coating core materials that are delicate and have crystalline structures that are difficult to wet and coat. The present invention now provides such a process for producing a stable sweetener delivery system. In this system, the sweetener core material is protected by a matrix coating that also has the ability to control the release of the sweetener. In particular, the present invention provides a process for producing a stable sweetener delivery system on a large scale.

The present invention therefore relates to a process for preparing a stable delivery system comprising a core material coated with a coating layer material consisting of a combination of an emulsifier with low molecular weight polyvinyl acetate, by

(a) melting and mixing the emulsifier and polyvinyl acetate;

(b) mixing the core material with the coating layer material of step (a);

(c) subjecting the mixture of step (b) to crude granulation at an elevated temperature in the range of 60º to 75ºC;

(d) subjecting the raw granules from step (c) to fine granulation to the desired particle size at a relatively lower temperature.

Step (a) is preferably carried out in a heated mixing tank.

Mixing in stage (b) is preferably carried out in a double planetary mixer, which is preferably connected via a discharge valve to the tank used in stage (a).

Step (c) is preferably carried out in a hot melt granulator.

Step (d) is preferably carried out in a vibrating granulator. The mixture from step (c) can be cooled by passing it through a cyclone separator. Step (d) is preferably carried out at a temperature in the range of 20 to 35ºC.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a photomicrograph of polyvinyl acetate coated saccharin crystals (x40) having a particle size in the range of 10µm to 610µm prepared by the process according to the invention.

Figure 2 is a photomicrograph of polyvinyl acetate coated saccharin crystals (x40) having a particle size in the range of 15µm to 645µm prepared by the process of the present invention.

Figure 3 shows a microphotograph of polyvinyl acetate coated saccharin crystals (x40) with a particle size in the range of 15 µm to 1,100 µm, which were produced by the process according to the invention.

Figure 4 shows a microphotograph of polyvinyl acetate coated saccharin crystals (x40) with a particle size in the range of 15 µm to 830 µm, which were produced by the process of the invention.

In particular, the present invention relates to a method with the steps

(A) providing the following ingredients in weight percent, based on the weight of the sweetener delivery system: (a) at least one solid natural or artificial, high intensity sweetener in an amount of 0.01 to 50%; (b) an emulsifier in an amount of 0.5 to 20%; and (c) polyvinyl acetate having a molecular weight in the range of 2,000 to 14,000 in an amount of 40% to 93%, and

(B) coating the sweetener with a polyvinyl acetate matrix coating and granulating the coated sweetener.

The procedure is as follows:

(a) melting and mixing the polyvinyl acetate with the emulsifier and mixing in the sweetener to form a homogeneous mixture in a heated mixing tank with a discharge valve in a double planetary mixer;

(b) Transferring the mixing tank containing the homogeneous mixture to a direct discharge system containing a hydraulic discharge plate that can be inserted (suitably) into the interior of the mixing tank and hydraulically discharging or expelling the mixture from the mixing tank via the discharge valve into an air- and water-cooled hot melt granulator,

(c) granulating the mixture into particles in the hot melt granulator;

(d) cooling the particles and transferring them from the hot melt granulator to a vibrating granulator by passing the particles through a cyclone separator and

(e) Granulating the particles in the vibrating granulator to a desired final particle size.

The applicant has found that by granulating the delivery system of the invention in two separate stages and carefully controlling the temperature of the delivery system during each granulation stage, the delivery system can be manufactured on a large scale. Known methods for producing the delivery system cool the sweetener melt to room temperature before the solid formed is ground to the desired particle size. Since the grinding a solid block of a sweetener on a large scale is dangerous, uneconomical and impractical, the applicant uses, in a first stage, a rough granulation of the melted encapsulated core material in a hot melt granulator at a controlled elevated temperature, before, in a second stage, a fine granulation of the solid, coarsely granulated, encapsulated core material is carried out in a vibrating granulator at a controlled lower temperature. Such a two-stage granulation of the melted core material enables the production of encapsulated core material on a large scale. Furthermore, since a rough granulation is carried out in a first stage, the applicant can carry out the fine granulation in a vibrating granulator in the second stage. This gives higher yields of granulated core material by avoiding the fine dust formed in an impact mill as used in the known processes.

The delivery system of the invention can be prepared by melting pieces of polyvinyl acetate (110°C to 120°C) in a jacketed mixing tank (with a discharge valve) of a double planetary mixer. The melted polyvinyl acetate material can then be further mixed for about ten (10) minutes to ensure the formation of a homogeneous mixture. While maintaining the temperature of the jacketed mixing tank, the emulsifier can be mixed into the melted polyvinyl acetate material. The melted mixture can then be stirred for an additional period of time, generally five (5) to twenty (20) minutes, to form a homogeneous mixture at a temperature of about 71°C. The sweetener, e.g., ground acesulfame-K, can then be added to the mixer and mixed for about five (5) to ten (10) minutes. The material should appear homogeneous and have a temperature of no more than about 73ºC.

The mixing tank containing the molten core material can then be placed under the direct discharge system which discharges the material into a hot melt granulator at a specific rate and temperature. The direct discharge system contains a preferably heated hydraulic discharge plate which can be inserted into the mixing tank. The direct discharge system discharges the mixture from the mixing tank hydraulically through the discharge valve and a transition piece into an air and water cooled hot melt granulator. The transition piece converts the round tubular molten discharge into a flat ribbon discharge. This ribbon discharge helps to optimize cooling by increasing the surface area per given product volume. The temperature and discharge rate of the material being discharged and the temperature and air flow rate are important. For example, a material at too low a temperature will have a high viscosity and can cause overloading of the discharge system. Material that is too hot may separate and may also require a lower discharge rate into the hot melt granulator to allow the granulator cooling system more time to cool the hot material. In a preferred embodiment, the temperature of the homogeneous mixture discharged from the mixing tank is between 65ºC and 73ºC, with the mixture being discharged from the mixing tank into the hot melt granulator at a rate of about 1.6 kg/min.

The material can then be granulated into particles in the hot melt granulator. According to a preferred embodiment, the granulated particles are passed through a screen attached to the hot melt granulator having a size in the range of 0.125 inch to 0.375 inch. Even better, the granulated particles are passed through a 0.5 inch screen attached to the hot melt granulator.

During granulation in the hot melt granulator, the particles are cooled. The particles are then cooled further and fed from the hot melt granulator via a cyclone separator into the hopper of a vibrating granulator. In a preferred embodiment, the temperature of the granulated particles transferred to the vibrating granulator is between 22ºC and 30ºC.

The vibrating granulator granulates the particles to the final desired mesh size. According to a preferred embodiment, the granulated particles are dropped through a sieve attached to the vibrating granulator having a mesh size between 24 mesh and 30 mesh, and preferably between 26 mesh and 28 mesh.

The delivery system of the invention comprises a core material and a coating layer material. The core material can be selected from a wide variety of materials, such as sweeteners, flavorings, drugs, pharmaceuticals and the like and mixtures thereof. In a single delivery system, one or more of these core materials can be present within a coating matrix. On the other hand, in a multiple delivery system, these core materials can also be present in combination, but separated by the matrix, coated.

The coating layer material is made from a combination of any emulsifier with low molecular weight polyvinyl acetate. These coating layers are virtually insoluble in water and protect the sweetener or other encapsulated material against hydrolytic degradation. Nevertheless, the coatings are sufficiently hydrophilic to swell in the presence of water and slowly release the core material. Glyceryl monostearate is a preferred emulsifier because it prevents hydrolysis of the polyvinyl acetate into acetic acid and polyvinyl alcohol.

The delivery system can be used in any food or nutritional product, in chewing gum, in candy, in personal care products, in pharmaceutical preparations, in dentifrices, mouthwashes and the like in which protection of an artificial sweetener against moisture is desired. The coating layers do not cause caries. Polyvinyl alcohol shows no or at most a low cold flow during prolonged storage at room temperature. The method according to the invention for producing the delivery system also does not require any solvents.

According to a preferred embodiment, the delivery system comprises

(a) at least one solid natural or artificial, high intensity sweetener selected from the group amino acid based sweeteners, dipeptide sweeteners, glycyrrhizin, saccharin and its salts, acesulfame salts, cyclamates, steviosides, thallin, dihydrochalcone compounds and mixtures thereof;

(b) an emulsifier present in an amount of 0.5 to 20% by weight of the sweetener delivery system, selected from the group consisting of lecithin, stearate esters, palmitate esters, oleate esters, glyceride esters, glyceryl monostearate, hydrogenated soybean oil (Durkee 17), sucrose polyesters, polyglycerol esters, and mixtures thereof; and

(c) polyvinyl acetate having a molecular weight of 2,000 to 14,000, preferably 2 to 12,000, in an amount of 40 to 93% by weight of the sweetener delivery system.

Preferably, the emulsifier is a combination of glyceryl monostearate and hydrogenated Soybean oil present in an amount of 2 to 15% by weight based on the weight of the delivery system.

According to another embodiment, waxes can also be accommodated in the delivery system. These waxes can be selected from the group of animal waxes, vegetable waxes, synthetic waxes, petroleum waxes and mixtures thereof.

The sweetener (sweetener) core component can be selected from solid natural or synthetic sweeteners with the ability of imparting high intensity sweetness. These sweeteners are selected from the group of amino acid-based sweeteners, dipeptide sweeteners, glycyrrhizin, saccharin and its salts, acesulfame salts, cyclamates, steviosides, thallin, dihydrochalcone compounds and mixtures thereof. According to a preferred embodiment, the high intensity sweetener is selected from the group of aspartame, saccharin and its salts, a mixture of aspartame and saccharin and a mixture of aspartame and saccharin together with acesulfame-K.

Generally, the delivery system will use a sufficient amount of the intense sweetener to provide the desired level of sweetness. This amount will vary depending on the sweetener selected. Preferably, the intense sweetener is present in an amount of 0.01 to 30% by weight based on the weight of the delivery system. Aspartame and saccharin and their salts are the preferred sweeteners. They may be present in an amount of 0.01 to 50, preferably 2 to 10, preferably 4 to 6% by weight based on the weight of the sweetener delivery system. In a preferred embodiment, the high intensity sweetener consists of a mixture of aspartame in an amount of up to 25% by weight and saccharin in an amount of 1 to 50% by weight of the sweetener. delivery system. In another preferred embodiment, the mixture mentioned additionally contains acesulfame-K in an amount of 0.1 to 50% by weight of the sweetener delivery system. The final product may also contain other sweeteners in quantities customary in the industry. The exact range of quantities for each type of sweetener is known in the relevant art and is not the subject of the present invention.

A particularly effective combination of sweeteners is aspartame, sodium saccharin and acesulfame-K (potassium acesulfame). Saccharin and its salts and acesulfame salts can be used in amounts of 5 to 50% by weight of the delivery system. Aspartame can be used in amounts up to 15% by weight when used in this combination. Prior to incorporation into the delivery system, one or more of the sweeteners can be in encapsulated form, thereby delaying the release of the sweetener and prolonging the perceived sweetness and/or staggering the release. The combination of two or more sweeteners alone or as part of the delivery system can also improve the sweetness intensity as a result of a synergistic effect. Examples of synergistic combinations are saccharin-aspartame, saccharin-potassium acesulfame and saccharin-aspartame-potassium acesulfame.

The delivery system according to the invention is in powder or granular form. The particle size is not critical for the delivery system and can be adjusted to suit a specifically desired release rate and mouth feel depending on the carrier in which the carrier system is incorporated. The coating matrix is suitable for a wide variety of core materials, e.g. spray-dried flavorings, pharmaceuticals and other particulate Materials that require a coating for protection, controlled release or taste masking.

Once prepared, the delivery system of the invention can be stored for future use or combined in effective amounts with conventional additives, e.g., pharmaceutically acceptable carriers or confectionery ingredients, to prepare a wide variety of edible compositions, e.g., foods, beverages, jellies, extracts, hard and soft confectionery products, orally administered drug preparations, and hygiene products such as toothpastes, dental lotions, mouthwashes, and chewing gums.

The amount of the delivery system of the invention in an edible mass is sufficient to sweeten the edible mass. The exact amount of the delivery system is a matter of preference and depends on factors such as the type of mass-providing agent or carrier used in the preparation and the level of sweetness desired. Thus, the amount of the delivery system can be varied to achieve (exactly) the result desired in the final product. Such variations are within the skill of the art without undue experimentation. Typically, the amount of sweetener delivery system normally contained in an edible mass or preparation is 10 to 50% by weight of the edible mass.

The present invention also extends to processes for preparing the edible masses or preparations. In such a process, a preparation is obtained by mixing an effective amount of the delivery system of the invention with a pharmaceutically acceptable carrier or confectionery material and the other ingredients of the ultimately desired edible preparation. Other ingredients are usually incorporated into the preparation taking into account the nature of the desired preparation and the The edible preparations ultimately obtained can be prepared without difficulty by methods known in food technology and in the pharmaceutical field. According to a further embodiment, the present invention relates to a method for sweetening an edible preparation by mixing an effective amount of the delivery system with the edible (base) mass.

An important aspect of the present invention relates to an improved chewing gum composition containing the delivery system of the invention and a method of preparing the chewing gum composition, including both chewing gum and bubble gum formulations. Typically, the improved chewing gum compositions contain a gum base, an effective amount of the delivery system of the invention, and various other additives.

The chewing gum preparations can be low-calorie chewing gums with high contents of chewing gum base with improved hydrophilic character. These low-calorie chewing gums contain a gum base in an amount of 50 to 95, expediently 50 to 85, preferably 60 to 70% by weight of the chewing gum preparation. If a low-calorie product is not desired, the chewing gum preparation can contain smaller amounts of chewing gum base. These chewing gums then contain a chewing gum base in an amount of up to 55, expediently 15 to 40, preferably 20 to 35% by weight of the chewing gum preparation.

Chewing gum preparations with a high proportion of chewing gum base with improved hydrophilic character are described in detail in US-PS 4,872,884.

The term "reduced calorie preparation" means here and hereinafter a preparation or mass having a calorific value of 2/3 or less of that of a conventional preparation. The term "solid chewing gum" or "rubbery chewing gum" means a chewing gum preparation which requires a strong use of the masseter muscles for chewing or a preparation which provides a rubber ball which is difficult to deform and has high elasticity and strong bounce.

Gum bases with enhanced hydrophilic character include, for example, polyvinyl acetate gum bases, which may also contain a low melting wax. Such gum bases do not require a high level of bulking agent to plasticize the gum base and soften the gum during chewing. These gum bases can be used in chewing gum formulations in place of bulking agents and/or bulking sweeteners in larger than normal amounts to provide reduced calorie chewing gums with high base and low bulking agent content without rubbery or firm chewing characteristics. These gum bases have stronger hydrophilic properties than conventional chewing gum bases and appear to increase in size during chewing, releasing flavorings and sweeteners normally trapped in the gum base while maintaining a soft chewing texture. Low-calorie chewing gum preparations produced in larger quantities using such gum bases are less hygroscopic (i.e. they absorb less moisture) and less susceptible to molding than comparable low-calorie chewing gum preparations, while having comparable strength and structure.

In one embodiment, the invention relates to a low-calorie chewing gum mass made from

(A) based on the weight of the chewing gum composition, 40 to 75 weight percent of a gum base comprising (a) an elastomer in an amount of 0.5 to 20 weight percent of the gum base, (b) polyvinyl acetate polymer having an average molecular weight in the range of 35,000 to 55,000 in an amount of 10 to 25 weight percent of the gum base, (c) an acetylated monoglyceride in an amount of 4.5 to 10 weight percent of the gum base, (d) a wax having a melting point below about 60°C in an amount of 6 to 10 weight percent of the gum base, and (e) a material selected from the group consisting of elastomer solvents, emulsifiers, plasticizers, fillers, and mixtures thereof in an amount that brings the total weight of the gum base to 100 weight percent. the rubber base;

(B) a bulking agent in an amount of up to 60% by weight of the chewing gum preparation and

(C) an effective amount of a sweetener delivery system comprising L-α-aspartyl-D-alanine-N-(2,2,4,4-tetramethyl-3-thietanyl)-amide and a hydrogenated starch hydrolysate.

The elastomers (rubbers) used in the gum base according to the invention vary greatly depending on a wide variety of factors, e.g. the type of gum base desired, the consistency of the gum preparation desired and the other components used in the preparation to produce the finished chewing gum product. The elastomer can consist of a water-insoluble polymer known in the relevant art and includes rubber polymers such as those used for chewing gum and bubble gums. Examples of polymers suitable in gum bases are natural and synthetic elastomers. For example, polymers suitable in gum base compositions include, without limitation, natural substances. (vegetable origin) such as chicle, natural rubber, crown gum, nispero, rosidinha, jelutong, perillio, nigergutta, tunu, balata, gutta-percha, lechicapsi, sorva, guttakay and the like, and mixtures thereof. Examples of synthetic elastomers include, without limitation, styrene/butadiene copolymers (SBR), polyisobutylene, isobutylene/isoprene copolymers, polyethylene and the like, and mixtures thereof.

The amount of elastomer used in the gum base depends on a variety of factors, such as the type of gum base used, the consistency of the desired gum formulation and the other components used in the composition to make the finished chewing gum product. Based on the weight of the gum base, the amount of elastomer present is 0.5 to 20, preferably 2.5 to 15% by weight.

The polyvinyl acetate polymer used in the gum base of the invention is a medium molecular weight polyvinyl acetate polymer, particularly a medium average molecular weight in the range of 35,000 to 55,000. This medium molecular weight polyvinyl acetate polymer preferably has a viscosity of about 35 s to about 55 s (ASTM designation D1200-82 using a Ford cup viscometer method). Based on the weight of the gum base, the amount of medium molecular weight polyvinyl acetate polymer present in the gum base is 10 to 25, preferably 12 to 27, weight percent.

The medium molecular weight polyvinyl acetate polymer can also be blended with a low molecular weight polyvinyl acetate polymer. The low molecular weight polyvinyl acetate polymer has an average molecular weight in the range of 12,000 to 16,000. This low molecular weight polyvinyl acetate polymer preferably has a viscosity of about 14 s to 16 s (ASTM designation D1200-82 using a Ford cup viscometer method). The low molecular weight polyvinyl acetate polymer is present in the gum base in an amount of up to 17, preferably from 12 to 17, weight percent of the gum base.

When a low molecular weight polyvinyl acetate polymer is mixed with a medium molecular weight polyvinyl acetate polymer, these polymers are used in a molar ratio of 1/0.5 to 1/1.5.

The medium molecular weight polyvinyl acetate polymer may also be blended with a high molecular weight polyvinyl acetate polymer. The high molecular weight polyvinyl acetate polymer has a medium average molecular weight in the range of 65,000 to 95,000. The high molecular weight polyvinyl acetate polymer is present in the gum base in an amount of up to about 5% by weight of the gum base.

The acetylated monoglycerides used according to the invention serve as plasticizers similar to the polyvinyl acetate polymer. While the saponification number of the acetylated monoglycerides is not critical, preferred saponification numbers are 278 to 292, 316 to 331, 370 to 380 and 430 to 470. A particularly preferred acetylated monoglyceride has a saponification number above about 400. Such acetylated monoglycerides generally have a degree of acetylation (percent acetylation) above about 90 and a Hydroxyl number less than approximately 10 (Food Chemical Codex (FCC) III/P508 and the revision of AOCS).

The use of acetylated monoglycerides, particularly triacetin, in the present gum base is preferred over the use of bitter polyvinyl acetate (PVA) plasticizers. The acetylated monoglycerides are present in the gum base in an amount of 4.5 to 10, preferably 5 to 9% by weight of the gum base.

The wax in the gum base according to the invention softens the polymeric elastomer mixture and improves the elasticity of the gum base. The waxes used have a melting or pour point below 60°C, preferably between 45°C and 55°C. A preferred wax is a low-melting paraffin wax. The wax is contained in the gum base in an amount of 6 to 10, preferably 7 to 9.5% by weight of the gum base.

In addition to the low-melting waxes, the rubber base can also contain waxes with a higher melting point in amounts of up to 5% by weight of the rubber base. Such high-melting waxes are beeswax, vegetable wax, candelilla wax, carnauba wax, most petroleum waxes and the like, as well as mixtures thereof.

In addition to the components mentioned, the rubber base can contain a wide variety of traditional ingredients, e.g. a component selected from the group consisting of elastomer solvents, emulsifiers, plasticizers, fillers and mixtures thereof. These ingredients can be contained in the rubber base in an amount that brings the total amount of the rubber base to 100%.

The rubber base may contain elastomer solvents to assist in softening the elastomer component.

Such elastomer solvents may consist of elastomer solvents known in the art, e.g., terpinene resins such as polymers of α-pinene or β-pinene, methyl, glycerin and pentaerythritol esters of rosins and modified rosins, and gums such as hydrogenated, dimerized and polymerized rosins, and mixtures thereof. Examples of elastomer solvents suitable for use in the present invention are the pentaerythritol ester of partially hydrogenated wood and gum rosin, the pentaerythritol ester of wood and gum rosin, the glycerol ester of wood rosin, the glycerol ester of partially dimerized wood and gum rosin, the glycerol ester of polymerized wood and gum rosin, the glycerol ester of tall oil rosin, the glycerol ester of wood and gum rosin and the partially hydrogenated wood and gum rosin and the partially hydrogenated methyl ester of wood and rosin, and the like, and mixtures thereof. The elastomer solvent may be present in the gum base in an amount of from 2 to 15, preferably from 7 to 11, percent by weight of the gum base.

The gum base may also contain emulsifiers to assist in dispersing the immiscible components into a single stable system. Emulsifiers suitable for use in the present invention are glyceryl monostearate, lecithin, fatty acid monoglycerides, diglycerides, propylene glycol monostearate and the like, and mixtures thereof. A preferred emulsifier is glyceryl monostearate. The emulsifier may be used in amounts of from 2 to 15, preferably from 7 to 11, weight percent based on the weight of the gum base.

The gum base may also contain plasticizers or softeners to provide a variety of desired texture and consistency properties. Due to the low molecular weight of these ingredients, the plasticizers and softeners penetrate into the basic structure of the gum base and make it plastic and less viscous. Suitable plasticizers and softeners are lanolin, palmitic acid, oleic acid, stearic acid, sodium stearate, potassium stearate, glyceryl triacetate, glyceryl lecithin, glyceryl monostearate, propylene glycol monostearate, acetylated monoglyceride, glycerin and the like, and mixtures thereof. Waxes, for example natural and synthetic waxes, hydrogenated vegetable oils, petroleum waxes such as polyurethane waxes, polyethylene waxes, paraffin waxes, microcrystalline waxes, fatty waxes, sorbitan monostearate, tallow, propylene glycol, mixtures thereof and the like can also be incorporated into the gum base. The plasticizers and softeners are used in the gum base in amounts of up to about 20%, preferably from about 9% to about 17% by weight, based on the weight thereof.

Preferred plasticizers are the hydrogenated vegetable oils and consist, for example, of soybean oil and cottonseed oil, which can be used alone or in combination. These plasticizers provide the gum base with a good texture and soft chewing properties. These plasticizers and softeners are used in amounts of from about 5 to about 14, preferably from about 5 to about 13.5, weight percent based on the weight of the gum base.

In a further preferred embodiment, the plasticizer consists of anhydrous glycerin, e.g. commercially available anhydrous glycerin of US Pharmacopeia (USP) purity. Glycerin is a syrupy liquid with a sweet, warm taste and a sweetness of about 60% of that of cane sugar. Since glycerin is hygroscopic, it is important to remove the anhydrous glycerin during manufacture. to keep the chewing gum preparation under anhydrous conditions.

A gum base making use of this invention can further contain effective amounts of bulking agents, e.g. mineral auxiliaries which can serve as fillers and structure-imparting substances. Suitable mineral auxiliaries or agents are calcium carbonate, magnesium carbonate, aluminum oxide, aluminum hydroxide, aluminum silicate, talc, tricalcium phosphate, dicalcium phosphate and the like, as well as mixtures thereof. These fillers or auxiliaries can be contained in the gum base masses in various amounts. Based on the weight of the gum base, the amount of filler used, if any, is 15 to 40, preferably 20 to 30% by weight.

The gum base may optionally contain a variety of traditional ingredients in effective amounts, such as colorants, antioxidants, preservatives, flavorings, and the like. For example, titanium dioxide and other colorants known for food, drug, and cosmetic preparations, known as F. D. & C. colors, may be used. An antioxidant, such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), propyl gallate, and mixtures thereof, may also be used. The gum base may also contain other chewing gum additives known to those skilled in the chewing gum art.

The manner in which the components of the rubber base are mixed together is not critical and can be carried out using standard methods and equipment known to those skilled in the art. In a typical process, an elastomer is mixed with an elastomer solvent and/or a plasticizer and/or a emulsifier and stirred for 1 to 30 minutes. After mixing is complete, the polyvinyl acetate component is mixed into the mixture. The medium molecular weight polyvinyl acetate is preferably mixed in before the addition of the optional low molecular weight polyvinyl acetate to prevent the formation of polyvinyl acetate pockets within the elastomer mixture. The remaining components, eg the low melting wax, are then mixed in either all at once or gradually, after which the rubber base mixture is again mixed for 1 to 30 minutes.

According to the invention, other gum bases with an enhanced hydrophilic nature and suitability for use in low-calorie chewing gum preparations in large quantities can also be used. Based on the weight of the chewing gum preparation, these gum bases are used in an amount of up to 99, preferably from 40 to 85 and preferably from 40 to 75% by weight. Suitable gum bases with an enhanced hydrophilic nature are known, for example, from US Pat. No. 4,698,223. The gum base is blended with the delivery system according to the invention and conventional additives, e.g. a bulking agent, to prepare a wide variety of sweetened chewing gum preparations.

The amount of gum base used in the chewing gum preparation depends on factors such as the type of gum base used, the desired consistency and the other components used to produce the finished chewing gum product. The gum base with increased hydrophilic character is contained in the chewing gum preparation in an amount of 50 to 95, preferably 50 to 85 and preferably 60 to 70% by weight of the chewing gum preparation.

In a further embodiment, the invention relates to a chewing gum preparation with smaller amounts of chewing gum base, ie the gum base is present in an amount of up to 55, preferably from 15 to 40 and preferably from 20 to 35% by weight of the chewing gum composition. In this embodiment the gum base comprises an elastomer and a variety of traditional ingredients, eg an elastomer solvent, waxes, emulsifiers, plasticizers or softeners, bulking agents, eg mineral adjuvants which may serve as fillers and texture-providing agents, colorants, antioxidants, preservatives, flavorings and the like, and mixtures thereof. Examples of these gum base components have already been given.

Once prepared, the gum base can be blended with the delivery system of the invention and conventional additives, e.g. a bulking agent, to produce a wide variety of chewing gum preparations.

In addition to the chewing gum base, the chewing gum preparation may contain a bulking agent. These mass-providing agents (carriers, extenders) can be water-soluble according to the invention and consist of sweeteners selected from the non-limiting group of monosaccharides, disaccharides, polysaccharides, sugar alcohols and mixtures thereof, randomly bound glucose polymers, e.g. polymers such as those sold under the trade name POLYDEXTROSE by Pfizer, Inc., Groton, Connecticut, isomalt (a racemic mixture of α-D-glucopyranosyl-1,6-mannitol and α-D-glucopyranosyl-1,6-sorbitol, sold under the trade name PALATINIT by Süddeutsche Zucker), maltodextrins, hydrogenated starch hydrolysates, hydrogenated hexoses, hydrogenated disaccharides, minerals such as calcium carbonate, talc, titanium dioxide, dicalcium phosphate, cellulose varieties and the like, and mixtures thereof. Based on the weight of the chewing gum preparation the mass-providing agents can be used in amounts of up to 60, preferably from 25 to 60% by weight.

Suitable bulking sugars include monosaccharides, disaccharides and polysaccharides such as xylose, ribulose, glucose (dextrose), mannose, galactose, fructose (levulose), sucrose (sugar), maltose, invert sugar, partially hydrolyzed starch and corn syrup solids and mixtures thereof. The preferred bulking sugars are mixtures of sucrose and corn syrup solids.

Suitable mass-increasing sugar alcohols include sorbitol, xylitol, mannitol, galactitol, maltitol and mixtures of the same. The preferred mass-increasing sugar alcohols are mixtures of sorbitol and mannitol.

Maltitol is a sweet, calorie-free, water-soluble sugar alcohol that has proven to be a suitable bulking agent in the preparation of calorie-free beverages and foods (see US Patent No. 3,708,396).

Maltitol is obtained by hydrogenation of maltose, the most common reducing disaccharide, in starch and other natural products.

The gum preparation can contain effective amounts of conventional additives selected from the group consisting of plasticizers, softeners, emulsifiers, waxes, fillers, mineral additives, flavoring agents (flavors, flavorings), colorants (colorants, dyes), antioxidants, acidifiers, thickeners and the like, and mixtures thereof. These ingredients are contained in the chewing gum preparation in such an amount that they bring the total amount of the chewing gum mass to 100%. Some of these additives can serve several purposes. For example, in sugar-free chewing gum preparations, a Sweeteners such as sorbitol or other sugar alcohols can also act as bulking agents.

The chewing gum preparation can also contain the plasticizers, softeners, mineral additives, waxes and antioxidants previously used in the gum base. Examples of other commonly used additives are emulsifiers such as lecithin and glyceryl monostearate, thickeners, alone or in combination with other softeners such as methylcellulose, alkynes, carrageenan, xanhan gum, gelatin, carob, tragacanth and carob, acidifiers such as malic, adipic, citric, tartaric and fumaric acid as well as mixtures of the same, and fillers, e.g. those previously mentioned in the category of mineral additives.

Flavoring agents that can be used are the flavors known to those skilled in the art, e.g. natural and artificial flavorings. These flavoring agents can be selected from synthetic flavor oils and flavoring aromatics and/or oils, oleoresins and extracts derived from plants, leaves, flowers, fruits and the like and combinations thereof. Non-limiting examples of flavoring oils are spearmint oil, cinnamon oil, wintergreen oil (methyl salicylate), peppermint oil, clove oil, bay oil, anise oil, eucalyptus oil, thyme oil, cedar leaf oil, nutmeg oil, clove pepper, oil of sage, mace, oil of bitter almonds and cassia oil. Also suitable as flavoring agents are artificial, natural and synthetic fruit flavors, such as vanilla and citrus oils, including lemon, orange, lime, grapefruit, and fruit essences, including apple, pear, peach, grape, strawberry, raspberry, cherry, plum, pineapple, apricot and the like.

These flavouring agents can be used in liquid or solid form alone or in mixtures. Usually Flavorings used are mint flavors such as peppermint, menthol, artificial vanilla, cinnamon derivatives and a variety of fruit flavors either alone or in mixtures.

Other suitable flavoring agents are aldehydes and esters, e.g. cinnamyl acetate, cinnamaldehyde, citral dietylacetal, dihydrocarvyl acetate, eugenyl formate, p-methylanisole, and the like. In general, any flavoring agent or food additive described in "Chemicals Used in Food Processing," Publication 1274, pages 63-258 of the National Academy of Sciences can be used.

Other examples of aldehyde aromatizing agents are - without limitation to the following examples - acetaldehyde (apple), benzaldehyde (cherry, almond), anisaldehyde (licorice, anise), cinnamaldehyde (cinnamon), citral, i.e. α-citral (lemon, lime), neral, i.e. β-citral (lemon, lime), decanal (orange, lemon), ethyl vanillin (vanilla, cream), heliotrope, i.e. piperonal (vanilla, cream), vanillin (vanilla, cream), α-amyl cinnamaldehyde (spicy fruity flavors), butyraldehyde (butter, cheese), valeraldehyde (butter, cheese), citronellal (modified, numerous types), decanal (citrus), aldehyde C-8 (citrus), aldehyde C-9 (citrus fruits), aldehyde C-12 (citrus fruits), 2- ethylbutyraldehyde (soft fruits), hexenal, i.e. trans-2 (soft fruits), tolylaldehyde (cherry, almond), veratraldehyde (vanilla), 2,6-dimethyl-5-heptenal, i.e. melonal (melon), 2,6-dimethyloctanal (green fruits) and 2-dodecenal (citrus fruits, mandarin), as well as dessert fillings made of cherry, grapes and strawberries, mixtures thereof and the like.

The flavouring agent can be used in liquid form and/or in dried form. When used in In the latter form, suitable drying means may be used, eg spray drying of the oil. Alternatively, the flavouring agent may be absorbed or encapsulated on water-soluble material, eg cellulose, starch, sugar, maltodextrin, gum arabic and the like. The practical means for producing such dried forms are known and do not form part of this invention.

The flavoring agents of the present invention may be used in numerous distinct physical forms known in the art to provide an initial "flavor burst" and/or a prolonged perception of the flavor. Without being limited thereto, such physical forms may include free forms, e.g., spray dried, powdered or beaded forms, and encapsulated forms, as well as mixtures thereof.

Encapsulated flavor delivery systems comprise a hydrophobic matrix of fat or wax enveloping a sweetener or flavor core. The fats can be selected from any number of common materials, e.g. fatty acids, glycerides or polyglycerol esters, sorbitol esters and mixtures thereof. Examples of fatty acids are hydrogenated and partially hydrogenated vegetable oils such as palm oil, palm kernel oil, peanut oil, rapeseed oil, rice bran oil, soybean oil, cottonseed oil, sunflower oil, safflower oil and mixtures thereof. Suitable glycerides are monoglycerides, diglycerides and triglycerides.

Suitable waxes can be selected from the group of natural and synthetic waxes and mixtures thereof. Non-limiting examples are paraffin wax, petrolatum, carbowax, microcrystalline wax, beeswax, carnauba wax, candelilla wax, lanolin, Bay wax, sugar cane wax, spermaceti wax, rice bran wax and mixtures thereof.

Based on the weight of the encapsulated system, the fats and waxes may be used individually or in combination in amounts of from about 10 to about 70, and preferably from about 40 to about 58, weight percent. When used together, the fat and wax are preferably present in a ratio of from 70/10 to 85/15.

Typical encapsulated flavorant delivery systems are known from U.S. Patent Nos. 4,597,970 and 4,722,845.

The amount of flavoring agent used is normally a matter of preference and depends on factors such as the type of finished chewing gum formulation, the individual flavor, the gum base used and the flavor strength desired. Thus, the amount of flavoring agent can be varied to achieve the desired result in the final product. Such changes are within the skill of the art without the need to conduct undue experimentation. In gum formulations, the flavoring agent is present in amounts of from 0.02 to 5, conveniently from 0.1 to 2 and preferably from 0.8 to 1.8% by weight of the chewing gum formulation.

The colorants useful in the present invention are used in amounts effective to provide the desired color. These colorants include pigments which can be incorporated into the gum composition in amounts up to about 6% by weight (of the gum composition). A preferred pigment, titanium dioxide, can be incorporated in amounts up to about 2%, preferably less than about 1% by weight of the gum composition. The colorants also include natural food colors and dyes suitable for food, drug and cosmetic preparations. These dyes are available as FD & C. dyes and pigment colors are known. The substances acceptable for the uses mentioned are preferably water soluble. Non-limiting examples of these are the indigoid dye known as FD & C. Blue No. 2, which is the disodium salt of 5,5-indigotine disulfonic acid. Similarly, the dye known as FD & C. Green No. 1 consists of a triphenylmethane dye, namely the monosodium salt of 4-[4-(N-ethyl-p-sulfoniumbenzylamino)-diphenylmethylene]-[1-(N-ethyl-Np-sulfoniumbenzyl)-δ-2,5-cyclohexadienimine]. A full listing of all FD & C. dyes and their corresponding chemical structures can be found in Kirk-Othmer's Encyclopedia of Chemical Technology, Third Edition, Volume 5, pages 857 to 884.

Oils and fats suitable for use in rubber preparations are partially hydrogenated vegetable or animal fats, such as coconut oil, palm kernel oil, beef tallow, lard and the like. When used, these components are generally present in amounts of up to 7, preferably up to 3.5% by weight of the rubber preparation.

In accordance with the invention, effective amounts of the delivery system of the invention can be mixed into the chewing gum composition. The exact amount of delivery system used is normally a matter of preference and will depend on factors such as the particular gum composition being prepared, the type of bulking agent or carrier used, the type of flavoring agent used and the intensity of sweetness desired. Thus, the amount of delivery system can be varied to achieve the desired result in the final product. Such changes are within the skill of the art without undue experimentation. Based on the weight of the chewing gum composition, the amount of delivery system in the chewing gum composition is 1 to 25, preferably 2 to 20 and preferably 5 to 15 wt.%.

The present invention further relates to a process for producing improved chewing gum preparations, including both chewing gum and bubble gum formulations. The chewing gum preparations can be produced by standard processes known to those skilled in the art in apparatus known to those skilled in the art. A device suitable for the invention consists of a mixing and heating device known in the chewing gum industry. Consequently, the person skilled in the art has no difficulty in choosing the specific device.

In such a process, a chewing gum preparation is obtained by mixing the gum base with the delivery system and the other ingredients of the final desired chewing gum preparation. Other ingredients are usually incorporated according to the nature of the desired preparation in a manner known to those skilled in the art. The final desired chewing gum preparations can be prepared by methods well known in the food technology and chewing gum arts.

For example, the rubber base is heated to a temperature high enough to soften the base without affecting its physical and chemical makeup. The optimum temperatures used depend on the composition of the rubber base used. Such temperatures can be easily determined by the expert without undue experimentation.

The rubber base is usually melted at temperatures in the range of 600 to 120ºC for a time sufficient to melt the rubber base. For example, the rubber base can be melted under these conditions for about 30 minutes immediately before portion-wise mixing with the remaining ingredients of the gum composition, e.g. the plasticizer, softener, bulking agent and/or fillers, colorants and flavorings, are heated to plasticize the mixture and to adjust the hardness, viscoelasticity and moldability of the base. Finally, the delivery system containing the core material is added and mixed for 1 to 10 minutes. The delivery system is added as the last ingredient. Mixing is continued until a uniform mixture of the gum composition is obtained. The final gum temperature is 39 to 51ºC. The gum composition can then be molded into the desired chewing gum shape.

According to a preferred embodiment, the invention relates to a process for producing a chewing gum mass with a stable sweetener delivery system in the following steps:

(1) Preparing a stable sweetener delivery system by (A) providing the following ingredients in percentages by weight of the sweetener delivery system:

(a) 0.01 to 50% by weight of at least one solid natural or artificial high intensity sweetener;

(b) 0.5 to 20% of an emulsifier and

(c) about 40 to 93% polyvinyl acetate having a molecular weight in the range of 2,000 to 14,000, and

(B) coating the sweetener with a polyvinyl acetate matrix coating and granulating the coated sweetener by

(a) melting and mixing the polyvinyl acetate with the emulsifier and mixing in the sweetener to form a homogeneous mixture in a heated mixing tank with a discharge valve in a double planetary mixer;

(b) transferring the mixing tank containing the homogeneous mixture to a direct discharge system containing a hydraulic discharge plate that can be inserted (suitably) into the interior of the mixing tank and hydraulically discharging or expelling the mixture from the mixing tank via the discharge valve into an air- and water-cooled hot-melt granulator;

(c) granulating the mixture into particles in the hot melt granulator;

(d) cooling the particles and transferring them from the hot melt granulator to a vibrating granulator by passing the particles through a cyclone separator and

(e) granulating the particles in the vibrating granulator to a desired final particle size; and

(2) Mixing the stable sweetener delivery system into a homogeneous mixture of gum base and remaining gum ingredients and

(3) Forming the mixture into suitable chewing gum shapes.

Preferably, the temperatures of the homogeneous mixture in step (1) (B) (a) are no more than about 73°C and in step (1) (B) (b) are from 65° to 73°C. Preferably, the mixture is transferred from the mixing tank to the hot melt granulator at a rate of about 1.6 kg/min. Preferably, the granulated particles in step (1) (B) (c) are passed through a 0.25 inch mesh screen attached to the hot melt granulator. Preferably, the temperature of the granulated particles in step (1) (B) (d) transferred to the vibrating granulator is from 22° to 30°C. Preferably, in step (1) (B) (e) the granulated particles are passed through a sieve attached to the vibrating granulator with a mesh size of between 24 mesh and 30 mesh, in particular between 26 mesh and 28 mesh.

The present invention is further illustrated by the following examples, which are not limiting in scope to the claims. Unless otherwise stated, all "parts" and "percents" in the examples and in the description refer to the weight of the finished preparation.

EXAMPLE 1

This example illustrates the improved process according to the present invention for producing a stable sweetener delivery system on a commercial scale.

Polyvinyl acetate was run through a crusher (lump crusher grinder, model 9 x 12 single rotor device, Lukens Company, 212 South Oak Street, Durhand, Michigan 48429) to produce approximately one inch pieces. The crushed polyvinyl acetate (71.83 kg, 158.32 lbs) was charged to the mix tank of a double planetary mixer (Ross model HDM-40 with stainless steel agitators, a jacketed high pressure tank, a discharge valve, and a variable speed motor). The control values on a Sterl-Tronic hot water heater (model S8424-AIX) were set as follows: Zone 1 (discharge valve) - 148ºF. (64ºC) and Zone 2 (mix tank) - 300ºF. (150ºC).

With the mixer closed, heating was continued until the polyvinyl acetate melted. The mixture temperature was then adjusted to 115ºC ± 5ºC and the mixture was mixed at low speed, approximately 8.7 rpm, for ten (10) minutes until a uniform mixture was formed.

The Zone 2 heater was set at 65ºC (148ºF.). Partially hydrogenated soybean oil (Durkee 17, 11.34 kg, 25.00 lbs) and glycerin monostearate (11.34 kg, 25.00 lbs) were added through the mixer inlet at low mixing speed (about 8.7 rpm) and mixing continued for about ten (10) minutes. After increasing the mixer speed to 12 rpm, mixing continued for five (5) minutes. The temperature was set at 71ºC ± 2ºC and mixing continued until a homogeneous mixture was obtained.

At a reduced mixing speed (approximately 8.7 rpm), ground Acesulfame-K (18.91 kg, 41.38 lbs) was added through the mixer inlet, followed by approximately ten (10) minutes The temperature was adjusted to a maximum of about 73ºC with continued mixing and cooling, after which mixing was continued until a homogeneous mixture was obtained.

The mix tank containing the melted mixture was then transferred to a direct discharge system (Ross Direct Discharge System, Model 40 gallon DISCH, Charles Ross & Son Company, 710 Old Willets Path, P.O.Box 12308, Hauppauge, New York, 11788-0615, stainless steel, heated platen, with adjustable discharge rate sized to match the configuration of the mix tank in the hot melt granulator). The water in the mix tank jacket was circulated at a temperature of 65ºC (148ºF.) to maintain the temperature of the sweetener batch between about 65ºC and about 73ºC.

The mixture in the mix tank was hydraulically discharged at a speed set at 4.5 (about 4 lbs/min, about 1.6 kg/min) and at a temperature of about 70ºC through a 3 inch x 0.26 inch jacketed transition piece maintained at a temperature of 65ºC directly into the inlet of a hot melt granulator unit (Polymer Systems, 54 Fuller Way, Berlin, Connecticut 06037, HMG-1010W, 750 cfm blower equipped with a 0.25 inch screen, Model 100 Cyclone, long conical shape). The hot melt granulator was set at a maximum air temperature of 700 F., a minimum air velocity of 4,500 feet per minute, an air flow of 750 cubic feet per minute, and a cooling water return at a temperature of about 50ºC to about 100ºC. The discharge speed can be adjusted to maintain a balance of product flow between the hot melt granulator and the oscillating granulator.

The approximate particle size distribution of the material separated by the cyclone separator from the hot melt granulator using an ATM sonic sieve operated at an amplitude of 7 for ten (10) minutes was as follows: US Standard Sieve No. Percent Retained

The particles from the hot melt granulator were cooled and transferred to a vibrating granulator by passing them through a cyclone separator. In the vibrating granulator, which had a 26 mesh screen, the particles were granulated to the desired final particle size. In a preferred embodiment, the temperature of the granulated particles transferred to the vibrating granulator is from about 220°C to about 300°C while the granulated particles are passed through a 26 mesh screen attached to the vibrating granulator.

The approximate particle size distribution of the final product obtained from the vibrating granulator using an ATM sonic sieve operated at an amplitude of 7 for ten (10) minutes was as follows: US Standard Sieve No. Percent Retained

The sieve of the vibrating granulator can be changed to obtain the required particle size distribution.

Claims (17)

1. A method for preparing a stable delivery system comprising a core material coated with a coating layer material consisting of a combination of an emulsifier with low molecular weight polyvinyl acetate, by (a) melting and mixing the emulsifier and polyvinyl acetate; (b) mixing the core material with the coating layer material of step (a); (c) subjecting the mixture of step (b) to crude granulation at an elevated temperature in the range of 65º to 73ºC; (d) cooling the granules; and (e) carrying out fine granulation on the raw granulate from step (c) to the desired particle size. 2. A method for preparing a stable sweetener delivery system comprising a core material coated with a coating layer material consisting of a combination of an emulsifier with low molecular weight polyvinyl acetate, by (a) melting and mixing the polyvinyl acetate with the emulsifier and mixing in the core material to form a homogeneous mixture in a heated mixing tank with a discharge valve in a double planetary mixer; (b) Transferring the mixing tank containing the homogeneous mixture to a mixing tank containing a hydraulic discharge plate which can be inserted into the interior of the mixing tank. Direct discharge system and hydraulic discharge or expulsion of the mixture from the mixing tank via the discharge valve into an air and water cooled hot melt granulator; (c) granulating the mixture into particles in the hot melt granulator; (d) cooling the particles and transferring them from the hot melt granulator to a vibrating granulator by passing the particles through a cyclone separator; and (e) Granulating the particles in the vibrating granulator to a desired final particle size. 3. A method according to claim 1 or 2, wherein the stable delivery system, based on its weight: (i) a core material of at least one solid natural or artificial high intensity sweetener in an amount of 0.01% to 50% and (ii) a coating layer material comprising an emulsifier in an amount of 0.5% to 20% and polyvinyl acetate having a molecular weight in the range of 2,000 to 14,000 in an amount of 40% to 93% includes. 4. The method of claim 3, wherein the high intensity sweetener is selected from amino acid based sweeteners, dipeptide sweeteners, glycyrrhicin, saccharin and its salts, acesulfame salts, cyclamates, steviosides, thallin, dihydrochalcone compounds and mixtures thereof. 5. The method of claim 4, wherein the high intensity sweetener comprises aspartame. 6. The method of claim 4, wherein the high intensity sweetener comprises saccharin or its salts. 7. The method of claim 4, wherein the high intensity sweetener consists of a mixture of aspartame in an amount of up to 25% by weight and saccharin in an amount of 1 to 50% by weight, each based on the delivery system. 8. The method of claim 7, wherein the high intensity sweetener additionally comprises acesulfame-K in an amount of 10 0.1 to 50% by weight of the sweetener delivery system. 9. A process according to any one of the preceding claims, wherein the emulsifier is selected from lecithin, stearate esters, palmitate esters, oleate esters, glyceride esters, sucrose polyesters, polyglycerol esters and mixtures thereof. 10. The method of claim 9, wherein the emulsifier is glyceryl monostearate and is present in an amount of 2 to 15% by weight of the delivery system. 11. A process according to any one of the preceding claims, wherein the polyvinyl acetate has a molecular weight in the range of 2,000 to 12,000. 12. A process according to any preceding claim, wherein the temperature of the mixture of step (a) is not more than 73°C. 13. A process according to any preceding claim, wherein the temperature of the mixture of step (b) is between 65ºC and 73ºC and the mixture is hydraulically fed from a mixing tank into a hot melt granulator. 14. A process according to any preceding claim, wherein the granulated particles of step (c) are passed through a 0.25 inch screen attached to a hot melt granulator. 15. A process according to any preceding claim, wherein the temperature of the granulated particles of step (d) transferred to an oscillating granulator is between 22ºC and 30ºC. 16. A process according to any preceding claim, wherein the granulated particles of step (e) are passed through a sieve of mesh size between 24 mesh and 30 mesh. 17. A method of making a chewing gum composition comprising preparing a stable delivery system according to any one of claims 1 to 16 and mixing the delivery system with a gum base and any other ingredients of the chewing gum composition.